Diesel fuel



Patented Dec. 23, 1941 DIESEL FUEL Leonard N. Leum, Lansdowne, Pa., assignor to The Atlantic Refining Company, Philadelphia, Pa., a corporation of Pennsylvania No Drawing.

Claims.

The present invention relates improvements in compression ignition fuels, and relates more particularly to the use of organic compounds of boron as ignition accelerators for hydrocarbon fuels of the compression ignition type.

A principal object of this invention is the improvement of Diesel engine fuels, and particularly of fuels adapted for use in high-speed compression ignition engines, whereby there is obtained a reduction in the ignition temperature of the fuel oil and a reduction of the delay period between the injection and ignition of the fuel oil.

According to-the present invention, compression ignition fuels, such as Diesel fuel oil having an initial boiling point of at least 300 F., may be altered in combustion characteristics byjthe Application September 24, 1938, Serial No. 231,595

addition of relatively small amounts of oil-soluble organic compounds of boron, and particularly oxygen-freeboron compounds, the structure of 'which is such that the boron atom thereof is directly attached to a carbon atom only singly bonded to carbon or other atoms.

More specifically, this invention is concerned with the improvement of the cetane number of compression-ignition fuels such as gas oil by the addition thereto ofsmall amounts of organic borine compounds and derivatives thereof. The

carbon atom only singly bonded to carbon or other atoms, are of particular utility as ignition accelerators for .compression ignition fuels. For.

example, borines containing alkyl groups, cycloparaffln groups, and aryl groups attachedto boran through a carbon atom other than a nuclear carbon atom are suitable for use as ignition accelerators, whereas those borines containing aryl groups directly bonded to boron are unsatisfactory for such purpose. I havefurther found that the branched-chain alkyl borines, such as the iso-alkyl borines, secondary alkyl borines, and, in particular, the tertiary alkyl borines, are superior to the borines containing normal alkyl groups, cycloparaffin groups, or methylene-substituted aryl groups, as ignition accelerators for Diesel fuels. In general, all of the borines which I have found suitable as ignition accelerators or cetane improvers are susceptible to atmospheric oxidation to a greater or lesser extent. Such susceptibilty may be markedly decreased, and in many cases entirely eliminated, by forming addition compounds of the borines with ammonia or substituted ammonias such as amines and nitrogenous organic bases, without decreasing the effectiveness of the borines as ignition accelerators.

Among the borine compounds and addition products thereof which may be employed in accordance with this invention are tri-methyl borine, tri-ethyl borine, tri-n-propyl borine, triisopropyl borine, tri-n-butyl borine, tri-isobutyl borine, tri-secondary butyl borine, tri-tertiary butyl borine, tri-n-amyl borine, tri-isoamyl' borine, tri-secondary amyl borine; tri-tertiary amyl borine, the hexyl borines, the heptyl borines, the octyl borines, and the higher members of this homologous series. Borines containing cycloparaflin groups, such as tri-cyclopentyl borine,-

tri-cyclohexyl borine, tri-cycloheptyl borine, and tri-cyclo octyl borine, as well as the methylene substituted aryl borines such as tri-benzyl borine, tri-mono-methyl benzyl borine, tri-dimethyl benzyl borine, and the like, may be employed in accordance with my invention. Any of the specific borines above mentioned, or others of similar type may be converted into borine-amine ads dition products of increased stability by treating the borines with organic amines. The borineamine addition compounds may be prepared by admixing the borine and amine, preferably diluted with an inert, low boiling solvent, heating the mixture at the refluxing temperature thereof to accelerate the formation of the addition compound, and thereafter removing the solvent by evaporation. Equimo lecular quantities of the borine and of the amine may be employed, al-

though it is preferable to use a slight excess of amine to insure complete conversion of the borine to the borine-amine compound. Excess amine may be removed from the product by evaporation, together with the solvent aforementioned. Such addition products may be exemplified by tri-methyl borine butylamine, tri-ethyl borine butylamine, tri-propyl borine butylamine, tri-butyl borine amylamine, tri-amyl borine amylamine, tri-hexyl borine amylamine, triheptyl borine hexylamine, tri-octylborine amylamine,- tri-cyclohexyl borine amylamine and tribenzyl borine amylamine. The amines to be employed are preferably those which have a carbon chain of sufllclent length to enhance the solubilpounds of boron otherthan the borines.

was obtained as a yellow oil which would not solidify even when cooled to F. The addition product was readily soluble in hydrocarbon oil and was stable to atmospheric oxidation at room temperature.

Among the advantages which accrue from the use of organic borines and derivatives thereof as ment with respect to ignition characteristics is expressed by an increase in the cetane number. In the table given below there are included, for purposes of comparison, several organic com- The base fuel oil to which the various boron compounds were added was a hydrocarbon oil having an A. P. 'I. gravity of 38.0 and a distillation range of from 330 F. to 561 F.

Weight Cetane ifi Cetane Compound added percent N o. of ba'se No.

. added blend increase fuel 0. 00 43. 7 Tri-n-butyl borine .v 0. 50 49. l 43. 7 5. 4 D0 1.00 55.2 43.7 11.5 D'O 2. 50 65. 7 43. 7 22.0

Trl-n-butyl borine n-arnylamine 0. 74 49. 2 43. 7 5. 5 Tri-isobutyl borine l. 00 55. 6 43. 7 ll. 9 Tri-tertiary butyl boriu 1.00 56. 7 43. 7 l3. 0 Tri-secondary octyl borine 1.00 57. 5 43. 7 l3. 8 Tri-cyclohexyl borine l. 00 54. 5 g 43. 7 l0. 8 Tri-benzyl borine l. 00 55. 2 43. 7 ll. 5 Tri-phenyl borine 1.00 44. 3 43. 7 0.6 Tri-naphthyl borine. l. 00 43. 9 43. 7 0. 2 Tri-n-butyl borate 1.00 44. 4 43. 7 0.7 Di-n-butyl boric acetatel. 00 43. 9 43. 7 0. 2

tached to a carbon atom only singly bonded to the other atoms, and particularly the borines other than the tri-aryl borines. And of the horines, it is to be noted that the branched-chain alkylborines, and especially the secondary and tertiary alkyl borines are superior to the straightchain alkyl borines, the cycloparaflin borines and the methylene-substituted aryl borines. The true aryl borines, such as tri-phenyl borine and trinaphthyl borine, as well as the esters of boric acid and alkyl boric acids are of little or no value as cetane improvers and are not considered within the scope of my invention.

The tri-n-butyl borine n-amylamine product referred to in the foregoing table was prepared as follows:

14.3 parts by weight of tri-n-butyl borine in solution in- 107 parts'by weight of diethyl ether was added to a solution of 8 parts by weight of n-amyl no in 36 parts by weight of diethyl ether. pon addition of the one solution to the other, a slight evolution of heat occurred, and the mixture was thereafter heated at refluxing temperature (35C.40C.) for about 50 minutes.

The e her and excess n-amylamine were then remove by evaporation, whereby the addition product, i. e., tri-n-butyl borine n-amyl-amine,

ignition accelerators in compression ignition fuels 'may be mentioned:

(l) Elimination of knocking and rough-running by decreasing the ignition lag.

(2) Easier starting due to the reduced spontaneous ignition temperatures of the blended fuel.

(3) Possibility of using inferior grade of fuel oil. By the addition of the accelerator, low grade fuels which at present are unsuitable for use in compression ignition engines, may be rendered equal or superior to high grade unblended fuels.

The fuel oils which are employed in accordance with this invention are hydrocarbon oils having an initial boiling point of at least 300 F., and a distillation range of the order of from about 300 F. to about 750 F. Such fuel oils are those suitable for combustion incompression ignition or Diesel engines, and include kerosine, gas oil, and higher boiling oil fractions, or mixtures thereof.

The above description and examples are to be taken as illustrative only and not as limiting the scope of the invention. Any modification or variation therefrom which conforms to the spirit of the invention is intended to be included within the scope of the claims.-

. What I claim is:

l. A compression ignition fuel comprising fuel voil having an initial boiling point of at least 300 1 and an organic borine-amine addition compound in quantity suflicient to substantially increase the cetane number of said fuel oil, the

structure of said borine compound being such .thatthe boron atom thereof is directly attached to a carbon atom only singly bonded to other atoms. 7

2. A compression ignition fuel comprising fuel 5 oil having an initial boiling point of at least 300 F. and a trialkyl borine-amine addition compound in quantity suflicient to substantially increase the cetane number of said fuel.

3. A compression ignition fuel comprising fuel oil having an initial boiling point of at least 300 F. and a branched-chain alkyl borine-amine ad- 'dition compound in quantity suflicient to sub- LEONARD N. LEUM.

stantially 

